Propeller mounting



March 15, 193,8. F. T. IRGENS 2,111,245

PROPELLER MOUNTING Filed April 5, 19:55

INVENTOR 21AM 7."

SYM wwwa i ATTORNEYS Patented Mar. 15, 1938 PATENT OFFICE PnoPELLEn MoNTiNG Finn T. Irgens, Wauwatosa, Wis., 'assigner to Gutboard Motors Corporation, Milwaukee, Wis., a corporation of Michigan Application April 5,

3 Claims.

This invention relates to improvements in propeller mountings.

It is the object of the invention to provide a propeller which will be self-balancing, free of vibration, and universally yieldable to elastically absorb shock. I accomplish these results by interposing an annularrubber cushion, or equiva- The present invention is peculiarly applicable to f outboard motor practice and to other marine devices wherein propellers are operated in shallow waters. y l

It is a further object of the invention to provide a propeller mounting combining the protection of a shear pin and a cushion drive.

In the drawing:

Figure l is anaxial section through a propeller and its mounting embodying the present invention.

Figure 2 is a transverse section on the line 42-2 of Fig. 1.

Like parts are identified by the same reference characters throughout the several views.

The housing or support 3 from which the propeller shaft 4 projects, is preferably shouldered at 6. The shaft turns in a bearing 3a which includes packing at 3b.y The externally projecting portion of the propeller shaft carries a sleeve at 6 constituting a universal propeller mounting which is secured against rotation on the shaft solely by means of a shear pin 1. A conventional cup-shaped retainer 8 prevents the loss of the shear pin and is held in place over the end of sleeve 6 by the usual retaining nut 9 which is screw threaded to the end of the propeller, shaft.

The propeller blades IIJ are carried by a hub IIk which is preferably extended to be complementary to the shouldered portion 5 of the housing, being spaced therefrom suiliciently at Il to permit the propeller to tilt bodily with respect to the shaft for a limited amount when the blades encounter an obstruction. The hub is spaced from the sleeve 6 by means of the bushing I2 xed in the hub as a part thereof and the annular cushion I3 which is preferably made of rubber or some like elastic material. In practice the cushion is usually vulcanized either to the sleeve 19'35, serial No'. 14,816

(c1. 11o-iva) 6 or the bushing I2 or both, but vulcanization is not essential since the rubber is inserted under compression sufficient to fix it against displacement with reference to either of these members. The degree-of compression is indicated by the 5 fact that the rubber annulus bulges at its ends in the manner clearly apparent in Fig. 1.

The rubber comprising the cushion is preferably soft enough to have a substantial yielding characteristic. In many instances when the pro-l l0 peller strikes a submerged obstacle such as a stump o-r a stone, the rubber cushion will permit the propeller to yield suiiiciently (as much as 90) to clear the obstacle without damage to the pin I which would otherwise have been sheared by 15 the impact. The mechanism driving the shaft 4 is likewise saved much shockwhere the rubber cushion is used, as compared with the shock which would be experienced if the propeller were coupled directly to the shaft solely by means of the 20 frangible pin 1. y

Aside from its ability to absorb shock imparted in a peripheral direction, the rubber cushion I3 has numerous advantages in that it permits the propeller to yield universally in any 26 direction with respect to the shaft I. It is seldom that a shock incurred by a propeller is directed peripherally thereof. The rubber cushion I3 permits the entire propeller to be displaced against elastic resistance diametrically of the shaft, and so also permits elastic displacement of the propeller angularly from the normalplane of rotation. Thus it saves the shaft from many shocks other than those from which the shaft is protected by a mere shear pin connection.v The propeller is in 35 balance about 'a point falling within the cushion because its blades are located in an annular series surrounding the cushion instead of being offset axially therefrom. s

The propeller is rotated at high speed and is 40 sometimes unbalanced either by reason of a de fect in manufacture or some injury which it has sustained. The use of a cushion at I3 leaves the propeller free to vibrate independently of the shaft in response to its eccentric loading, and 45 thereby saves the shaft and the associated mechanism from such vibration.

It very frequently happens that a propeller which has once encountered a submerged obstacle may have one of its blades or nukes bent so that its pitch is incorrect. The presence of the cushion I3 permits the propeller to adjust itself under such conditions to an angle with respect to its shaft such that the thrust delivered from all of the blades is uniform. This feature also eliminstesmuchvibrstionandwearoftheshaft f and associated mechanism which occur when the propeller has und bearings determining its posisaid hub being wholly dependent upon said cushion for its position rotatably and tiltably with respect to said drive shaft. and said cushion being suillciently elastic to accommodate self-adjustments of the propeller in equilibrium upon said sleeve and to allow a substantial torsional displacement of said hub relative to the drive shaft of such degree as to enable the propeller to clearl submerged obstructions, and also acting to prevent the shear pin from being broken when the propeller meets an obstruction. v

2. A'marine propeller assembly comprising in combination, a propeller having aset of blades and a hub, a drive shaft, a support for the drive shaft, said hub having its forward portion surrounding and spaced from said support to permit tilting of the hub, an annular cushion confined between said hub and said shaft at the rear of said support, said cushion arranged to form a supporting connection between said shaft and said hub and to provide a universal propeller mounting and an elastic driving connection from the drive shaft to nid propeller, said hub being wholly dependent upon said cushion for its position rotatably and tiltably with respect to said drive shaft, said blades being located in an annu- 'lar series surrounding the cushion so that the propeller is in balance about a point -falllng within they cushion, and said cushion being sumciently elastic to accommodate self-adjustments of theprojecting therefrom, an annular cushion upon the shaft, a propeller having its hub mounted on the cushion in spaced relation to the shaft and to the shaft support, and a set of blades located in an annular series surrounding the cushion so that the propeller is in balance about a point falling within the cushion, said cushion being confined between the propeller hub and shaft to provide an elastic driving connection from the drive shaft to the propeller, and a universal propeller mounting upon which said hub is wholly dependent for its position rotatably and tiltably with respect to said shaft, said cushion being suillciently'elastic to accommodate self-adJustlments of the propeller in equilibrium upon said cushion and to allow a substantial torsional displacement of said hubrelative to the shaft to a degree sumcient to enable the propeller to clear submerged obstacles. v

FINN T. IRGENS. 

